Field of the Invention
Exemplary embodiments of the present invention relate to a thin film transistor panel and a method for fabricating a thin film transistor panel.
Discussion of the Background
A flat panel display, such as a liquid crystal display (LCD) or an organic light emitting display (OLED), typically includes pairs of field generating electrodes and an electro-optical active layer disposed between each pair of field generating electrodes.
A pixel electrode, which is one electrode of the pair of field generating electrodes, can be connected to a switching element that transmits electrical signals to the pixel electrode. The electro-optical active layer operates in response to the electrical signal, thereby displaying images.
A thin film transistor (TFT) is typically used for the switching element that is connected to the pixel electrode. A TFT includes a gate electrode, a source electrode, a drain electrode, and an active layer disposed between the gate electrode and the source electrode and the drain electrode. The active layer may include amorphous silicon or polycrystalline silicon.
High-mobility TFTs should be used with larger flat panel displays. A TFT having an oxide semiconductor as an active layer has shown high performance. The typical TFT fabrication process involves depositing and patterning multiple layers. But when fabricating a TFT having source and drain electrodes on an oxide semiconductor active layer, the oxide semiconductor active layer may be damaged when forming the source and the drain electrodes, thereby degrading the TFT's characteristics.
To reduce or prevent this damage, as disclosed in JP 2005-285890, a channel protection layer may be formed on the oxide semiconductor active layer before forming the source and the drain electrodes. However, forming the channel protection layer on the oxide semiconductor active layer can increase the number of photolithographic processes used to manufacture the TFT, thereby increasing the time and cost to manufacture the TFT panel.